Combining Depth and Rate of Selenium Fertilizer Basal Application to Improve Selenium Content and Yield in Sweet Maize

Selenium-enriched sweet maize is an important product to alleviate selenium deficiency in the human body. In this study, the effects of the basal application of selenium fertilizer on the selenium content and yield of maize were analyzed in a 2-year field trial using a two-factor, five-level, split-area experimental combination design with a different selenium fertilizer application rate (150–750 kg ha−1) and depth (1–20 cm). It was found that the selenium application rate and depth significantly affected dry matter mass, selenium content, and selenium accumulation in maize. In particular, the Se3D4 treatment combination (a selenium application rate of 450 kg ha−1 and depth of 15 cm) performed the best in increasing the selenium content and yield of the maize grain. The 2-year data showed that the selenium content of maize grain under Se3D4 treatment reached 3.59 mg kg−1 and 3.24 mg kg−1, which were 13.63 and 13.70 folds as the control, respectively, and the yield reached 6.28 t ha−1 and 6.07 t ha−1, which were 24.35% and 33.30% higher than the control, respectively. Therefore, by optimizing the application rate and depth of selenium fertilizer, the selenium content and yield of maize can be significantly increased. The results of this study provide a theoretical basis for the precise application of selenium fertilizer in the biofortification of sweet maize.